Abstract Staphylococcus aureus is an important cause of bloodstream infections. Therefore, the main purpose of this work was to characterize a collection of 139 S. aureus isolates from bloodstream infections in two public hospitals in relation to their antimicrobial susceptibility profile, staphylococcal cassette chromosome mec types, and clonal relationship. Methicillin resistance and resistance to other 12 agents were accessed by the disk diffusion test. Minimum inhibitory concentration to mupirocin was also determined. The SCCmec types were accessed by multiplex PCR, and the clonal relationship was determined by pulsed field gel electrophoresis method and restriction modification system characterization. Besides, multilocus sequence typing was performed for representative methicillin-resistant S. aureus isolates. The military hospital showed a dissemination of the New York/Japan (USA100/ST5/CC5/SCCmecII) lineage associated to multidrug resistance, including mupirocin resistance, and the teaching hospital presented polyclonal and non-multidrug resistant MRSA isolates. Complete substitution of the Brazilian endemic clone by other lineages was found in both hospitals. These findings can highlight differences in policy control and prevention of infections used in the hospitals and a change in the epidemiological profile of MRSA in Brazilian hospitals, with the replacement of BEC, a previously well-established clone, by other lineages.

O papel dos antibióticos contendo sacarose na formação de cárie dentária é ainda controverso. Este estudo teve como objetivo investigar o efeito de dois antibióticos (amoxicilina / clavulanato de potássio suspensão oral), com e sem sacarose, na dureza do esmalte dental humano e na contagem de Streptococcus mutans no biofilme dental. Fragmentos de dentes decíduos (n = 72) foram revestidos com verniz deixando uma janela de exposição de 2,25mm de diâmetro. Os espécimes foram fixados em placas de poliestireno de 24 poços, contendo meio de cultura BHI. S. mutans (estirpes clínicas) representaram o inoculo para formar biofilmes sobre os fragmentos por 24 h. Doze fragmentos foram separados para a contagem inicial de microrganismos (baseline). Os restantes dos fragmentos foram divididos em 4 grupos (n = 12) de tratamento: G1 (Clavulin(r)), G2 (Betamox(r)), G3 (clorexidina 0,12%), G4 (sacarose a 10%). Todas as amostras tiveram sua área de controle (área coberta). A microdureza transversal (CSMH) foi avaliada para cada espécime. Todos os grupos tratados tiveram uma perda de dureza quando comparados com os seus respectivos controles (p <0,05). Ambos os fármacos inibiram o crescimento de S. mutans e não promoveram diferença da CSMH entre eles. Ambos os antibióticos eliminaram todo o biofilme formado, não promovendo assim, perda mineral do esmalte, independente da presença de sacarose na sua formulação.

The role of antibiotics containing sucrose on the formation of dental caries is still controversial. This study aimed to investigate the effect of two antibiotics (amoxicillin and potassium clavulanate suspension), with and without sucrose, on human dental hardness and Streptococcus mutans counts in dental biofilm. Primary tooth fragments (n=72) were coated with nail varnish leaving a window of 2.25 mm diameter. Specimens were fixed in 24-well polystyrene plates, containing BHI medium. S. mutans (clinical strains) represented the inoculum to form biofilm on the fragments for 24 h. Twelve fragments were separated for the initial count of microorganisms (baseline). The other fragments were divided into 4 groups (n=12) of treatment: G1 (Clavulin(r)), G2 (Betamox(r)), G3 (chlorhexidine 0.12%), G4 (sucrose 10%). All specimens had their self-control area (covered area). The cross-sectional microhardness (CSMH) was evaluated for each specimen. All the treated groups had a loss of hardness compared to their self-controls (p<0.05). Both drugs inhibited the S. mutans growth and promoted no CSMH difference among them. Both antibiotics eliminated all formed biofilm and did not cause mineral loss from the enamel, regardless the presence of sucrose in its formulation.

Staphylococcus aureus is an important cause of infections and HIV-infected individuals are frequently susceptible to this pathogen. The aim of this study was to perform a systematic review to identify both the risk factors associated with colonization/infection by methicillin-resistant S. aureus in HIV patients and the methods used for characterization of isolates. An electronic search of articles published between January 2001 and December 2013 was first conducted. Among 116 studies categorized as being at a quality level of A, B or C, only 9 studies were considered to have high methodological quality (level A). The majority of these studies were retrospective (4/9 studies). The risk factors associated with colonization/infection by S. aureus were use of antimicrobials (4/9 studies), previous hospitalization (4/9 studies) and low CD4+ T lymphocyte counts (<200 cells/μl) (3/9 studies). Culture in mannitol salt agar (3/9 studies) and the latex agglutination test (5/9 studies) were the main methods used for bacterial phenotypic identification. Genotypic profiles were accessed by pulsed-field gel electrophoresis (6/9 studies) and USA300 was the most prevalent lineage (5/9 studies). Most isolates were resistant to erythromycin (3/9 studies) and susceptible to vancomycin (4/9 studies). Ultimately, use of antimicrobials and previous hospitalization were the main risk factors for colonization/infection by methicillin-resistant S. aureus in HIV-infected individuals. However, the numbers of evaluated patients, the exclusion and inclusion criteria and the characterization of the S. aureus isolates were not uniform, which made it difficult to establish the characteristics associated with HIV patients who are colonized/infected by S. aureus.

INTRODUÇÃO: O gênero Staphylococcus é de grande importância devido a sua alta prevalência em infecções hospitalares e por apresentar taxas elevadas de resistência a oxacilina e a outros antimicrobianos. Assim, a avaliação da acurácia dos métodos fenotípicos usados para determinação do perfil de suscetibilidade a antimicrobianos é essencial para garantir a escolha da terapia mais adequada. MÉTODOS: Foram usadas 114 amostras de Staphylococcus sp (53 S. aureus e 61 SCN) na avaliação da acurácia dos métodos de difusão de disco, microdiluição em agar, ágar triagem oxacilina e sistema automatizado em comparação com a PCR para verificação da resistência a oxacilina. RESULTADOS: O gene mecA foi detectado em 48 (42,1%) amostras e 27 (23,7%) amostras apresentaram discrepância de resultados em pelo menos um dos métodos (74,1% SCN, 25,9% S. aureus). Para S. aureus, com exceção do Microscan Walkaway, todos os métodos apresentaram 100% de especificidade e sensibilidade. Já para os SCN, o sistema automatizado e o disco de cefoxitina apresentaram menor acurácia. CONCLUSÕES: O uso de dois métodos deve ser a melhor opção para a melhora da acurácia, principalmente quando o laboratório de diagnóstico utiliza somente sistema automatizado ou teste de difusão do disco de oxacilina. A associação destes métodos com outros apresentaram praticamente 100% de sensibilidade e especificidade em nosso estudo.

INTRODUCTION: The genus Staphylococcus is of great importance because of its high prevalence in hospital infections and because it presents high rates of resistance to oxacillin and other antimicrobials. Thus, evaluation of the accuracy of the phenotypic methods that are used to determine the profile of antimicrobial resistance is essential to ensure that the most appropriate therapy is chosen. METHODS: One hundred and fourteen strains of Staphylococcus sp (53 S. aureus and 61 CNS) were used to evaluate the accuracy of the methods of disk diffusion, agar microdilution, oxacillin screening agar and automated systems, in comparison with PCR for investigating resistance to oxacillin. RESULTS: The mecA gene was detected in 48 strains (42.1%), and 27 strains (23.7%) showed discrepant results in at least one of the methods (74.1% of CNS, 25.9% of S. aureus). For S. aureus, with the exception of the Microscan Walkaway, all the methods showed 100% specificity and sensitivity. In relation to CNS, the automated system and cefoxitin disk had lower accuracy. CONCLUSIONS: Use of two methods should be the best option for improved accuracy, especially when the diagnostic laboratory only uses an automated system or oxacillin disk diffusion test. Combination of these methods with others presented almost 100% sensitivity and specificity in our study.